The present invention relates to a peristaltic pump of the type used to propel liquid through a compressible tube or a conduit which includes at least a resiliently compressible sector or section. More particularly, the invention is directed to a peristaltic pump in which insertion of resiliently compressible tubing into during loading of the pump and withdrawal of the tubing from the pump housing is facilitated.
Pumps of the type in which the fluids or fluid-like materials being "moved" are isolated from and do not come into direct physical contact with cavities or mechanical elements of the pump itself are known in the art. Such pumps have been used in conjunction with the displacement of many different types of materials to be handled, and the pumps themselves have assumed many and varied mechanical arrangements and structures. Typical of a general type of pump of the class referred to are peristaltic, or hose, or tube-compressing pumps.
The peristaltic pumps commonly include a motor-driven hub or rotor which carries outwardly-directed, circumferentially-disposed, and annularly-spaced arms or compression rollers. As the driven hub rotates, the spaced rollers are brought sequentially into contact with so as radially and advancingly repetitively to compress (and to permit expansion of) a sector or lineal section of a resiliently compressible tube seated in and contiguously abutting and bearing against a bounding wall of an arcuate channel provided in the pump body or housing and having a generally uniform radius of curvature. The tubing-carried fluid is pumped through the tubing in the direction of the annular sequential movement of the compressing rollers.
The confined section of resilient tubing, while functioning effectively as part of the pump, serves to preserve a sealed and isolated fluid flow system in which the fluid is also protected against contact with the pump structure itself.
Peristaltic pumps of the type described have included spring mechanisms for resiliently biasing the tube-engaging and tubing-compressing rollers or arms radially outwardly toward a bounding wall of the arcuate channel and against the compressible section of tubing confined in the channel. The specific arrangements of such biasing springs have varied. Typical structures are described in U.S. Pat. Nos. 3,822,948; 3,963,023 and 4,210,138.
A significant problem in the effective utilization of peristaltic pumps is associated with the operational steps of loading the tubing into and removing the tubing from the pump body. The difficulty and inconvenience experienced are associated with effectively manipulating the tubing into place within the tubing-confining channel of the pump. The compression rollers or tube-compressing arms constitute mechanical impediments which interfere with the ease of insertion and the proper placement of the compressible tubing section into the pump housing.
For example, when peristaltic pumps are used in the medical field, including for urological procedures, it is necessary either physically radially to retract or to displace each interfering roller, in turn, against the significant opposing pressure of a spring which biases the compression arm or roller radially outwardly against the resilient tubing. Alternatively, it is necessary digitally to compress the tubing, at each of several annularly spaced positions of the tubing-receiving channel, so that the tubing can be properly and functionally seated and oriented. In carrying out either technique, the procedure invoked is time consuming. Moreover, a considerable degree of dexterity and skill is required. In some instances the necessary manipulation steps may even expose the doctor, nurse or medical technician to possible injury.
In specific prior art peristaltic or hose-type pumps it is known to provide mechanisms by which the squeezing rollers will be "lifted" or urged into a partially retracted mode in response to increased pressure in the fluid-carrying tube itself. Peristaltic pumps of the type in which the weight of the drive motor determines the force with which the pinching or occluding rollers bear against the housing-confined section of tubing are known in the art. In one such device, the motor has been mounted on a rocker arm so that, if necessary, pumping can be stopped quickly by lifting and supporting the rocker arm (and the motor assembly) functionally to disengage the compression rollers from the tubing section. However, neither this nor any other mechanical arrangement of prior art devices is directed to or serves to alleviate the difficulties inherent in loading the tubing sector into and removing the tubing from the pump assembly. It is, accordingly, a principal aim of the present invention to obviate the problems present in prior art peristaltic pumps and, particularly, the problems associated with insertion of the resiliently compressible tubing into and the removal of the tubing from such pumps.